Abstract: To improve the range resolution and suppress range-dimensional interferences,we proposed a new beamformer for active sonar signal processing,which is termed as the range-dimensional beamformer.The proposed beamformer extracts several sub-band components from single echo of the active sonar.Due to the frequency gaps between these sub-band components,their phase shifts form a complex geometric series,which is similar to the array manifold vector of a uniform linear array.Accordingly,borrowing from the traditional angle-dimensional beamformer,we propose the range-dimensional beamformer which can form a beampattern in the range dimension.The corresponding sample covariance matrix is constructed directly from the sub-band components;and the scanning vector is calculated according to their phase shifts at the center frequencies.We give both the expressions and processing procedures of the rangedimensional conventional beamformer and the range-dimensional adaptive beamformer.Furthermore,we give analyses on the processing performance of the range-dimensional beamformer.Numerical simulations and a tank experiment demonstrate the effectiveness of the proposed range-dimensional beamformer.